Use reference-equality when omitting validation rules during composition. (#3338)

* Use reference-equality when omitting validation rules during composition.

The previous technique for deciding which validation rules from
`specifiedSDLRules` to by-pass during
composition was leveraging a string-comparison against
`Function.prototype.name`.

As shown in #3335, that
technique breaks down under minification, when function names are often
munged to shorter alternatives.

As an alternative, we can import the rules and check them for reference
equality with greater success, since those will not be affected by
minification.

While the actual bug in #3335 was _not_ in this code, this code poses the
same hazard and would likely be affected as well (eventually, at least).

* Add changelog entry

Author: abernix

packages/apollo-federation/CHANGELOG.md

@@ -4,6 +4,8 @@
 
 > The changes noted within this `vNEXT` section have not been released yet.  New PRs and commits which introduce changes should include an entry in this `vNEXT` section as part of their development.  When a release is being prepared, a new header will be (manually) created below and the the appropriate changes within that release will be moved into the new section.
 
+- Use reference-equality when omitting validation rules during composition. [#3338](https://github.com/apollographql/apollo-server/pull/3338)
+
 ### v0.10.0
 
 > [See complete versioning details.](https://github.com/apollographql/apollo-server/commit/6100fb5e0797cd1f578ded7cb77b60fac47e58e3)

packages/apollo-federation/src/composition/rules.ts

@@ -1,27 +1,59 @@
 import { specifiedSDLRules } from 'graphql/validation/specifiedRules';
 
+/**
+ * Since this module has overlapping names in the two modules (graphql-js and
+ * our own, local validation rules) which we are importing from, we
+ * intentionally are very explicit about the suffixes of imported members here,
+ * so that the intention is clear.
+ *
+ * First, we'll import validation rules from graphql-js which we'll omit and
+ * replace with our own validation rules. As noted above, we'll use aliases
+ * with 'FromGraphqlJs' suffixes for clarity.
+ */
+
+import {
+  UniqueDirectivesPerLocation as UniqueDirectivesPerLocationFromGraphqlJs,
+} from 'graphql/validation/rules/UniqueDirectivesPerLocation';
+import {
+  UniqueTypeNames as UniqueTypeNamesFromGraphqlJs,
+} from 'graphql/validation/rules/UniqueTypeNames';
+import {
+  UniqueEnumValueNames as UniqueEnumValueNamesFromGraphqlJs,
+} from 'graphql/validation/rules/UniqueEnumValueNames';
+import {
+  PossibleTypeExtensions as PossibleTypeExtensionsFromGraphqlJs,
+} from 'graphql/validation/rules/PossibleTypeExtensions';
+import {
+  UniqueFieldDefinitionNames as UniqueFieldDefinitionNamesFromGraphqlJs,
+} from 'graphql/validation/rules/UniqueFieldDefinitionNames';
+
+/**
+ * Then, we'll import our own validation rules to take the place of those that
+ * we'll be customizing, taking care to alias them all to the same name with
+ * "FromComposition" suffixes.
+ */
 import {
-  UniqueTypeNamesWithFields,
-  MatchingEnums,
-  PossibleTypeExtensions,
-  UniqueFieldDefinitionNames,
-  UniqueUnionTypes,
-} from './validate/sdl';
+  UniqueTypeNamesWithFields as UniqueTypeNamesWithFieldsFromComposition,
+  MatchingEnums as MatchingEnumsFromComposition,
+  PossibleTypeExtensions as PossibleTypeExtensionsFromComposition,
+  UniqueFieldDefinitionNames as UniqueFieldDefinitionsNamesFromComposition,
+  UniqueUnionTypes as UniqueUnionTypesFromComposition,
+ } from './validate/sdl';
 
 const omit = [
-  'UniqueDirectivesPerLocation',
-  'UniqueTypeNames',
-  'UniqueEnumValueNames',
-  'PossibleTypeExtensions',
-  'UniqueFieldDefinitionNames',
+  UniqueDirectivesPerLocationFromGraphqlJs,
+  UniqueTypeNamesFromGraphqlJs,
+  UniqueEnumValueNamesFromGraphqlJs,
+  PossibleTypeExtensionsFromGraphqlJs,
+  UniqueFieldDefinitionNamesFromGraphqlJs,
 ];
 
 export const compositionRules = specifiedSDLRules
-  .filter(rule => !omit.includes(rule.name))
+  .filter(rule => !omit.includes(rule))
   .concat([
-    UniqueFieldDefinitionNames,
-    UniqueTypeNamesWithFields,
-    MatchingEnums,
-    UniqueUnionTypes,
-    PossibleTypeExtensions,
+    UniqueFieldDefinitionsNamesFromComposition,
+    UniqueTypeNamesWithFieldsFromComposition,
+    MatchingEnumsFromComposition,
+    UniqueUnionTypesFromComposition,
+    PossibleTypeExtensionsFromComposition,
   ]);